Association of sympathetic axons in denervated hippocampus to intracerebral vasculature. I. Fluorescence histochemistry combining glyoxylic acid and pontamine sky blue.

Combining glyoxylic acid and pontamine sky blue fluorescence methods allows simultaneous visualization of catecholamine fibers and the intra-hippocampal vascular bed. The normal noradrenergic innervation of the hippocampal formation is not closely associated with the vasculature in any region. However, following lesions of the septo-hippocampal fibers, norepinephrine-containing sympathetic fibers course along the penetrating arterioles into the parenchyma of regio inferior and the area dentata. Within the respective cell layers, the anomalous sympathetic axons collateralize freely, thus suggesting a dual relationship with the vasculature and with the neuropil of selective hippocampal zones.